Design Of Vibration Energy Harvester Research Articles

Tapered curved-beam hinges for electret-based vibration energy harvesting devices

Abstract Interests on vibration energy harvesting have been growing recently for various applications. One of the major development goals for vibration energy harvesters has been improvement in energy conversion efficiency. To pursue that goal, one of the main approaches has been to broaden the spectra of harvesters. Employment of nonlinear springs, such as curved-beam hinges, has proven to be effective for that purpose. The main contribution of the current study is to introduce a lateral taper to the curved beam so as to further optimize the harvester performances. Via numerical analysis by using stochastic differential equations, the study shows that at 0.05g of vibration strength, tapered curved-beam hinges can result in higher electric power output than the non-tapered ones. Deformation-induced stress was taken into consideration as well, in reference to the fracture strength of the material (single-crystal silicon). At lower vibration strength (0.02g), spring nonlinearity becomes weaker, and as a result, the narrowest curved-beam hinge produces the highest output power. Overall, the current study demonstrates that tapering of the curved beam can be a useful addition in the vibration energy harvester design.

Vibration energy harvester design and experimental study based on double-negative metamaterials

Vibration energy harvester design and experimental study based on double-negative metamaterials

Design and performance of a novel magnetically induced penta-stable piezoelectric energy harvester

The magnetically induced multi-stable piezoelectric vibration energy harvesters have garnered significant attention due to their strong nonlinear characteristics, wide operating bandwidths, and high electromechanical energy conversion efficiency. However, a traditional penta-stable design typically requires four rectangular external magnets. The excessive number of structural parameters amplify complexities in system optimization, dynamic analysis, and prototype installation, impeding harvester manufacturing and application. This study presents a novel penta-stable harvester design that utilizes interaction forces among a rectangular magnet and two annular magnets, resulting in a simplified system requiring only two external magnets. This design approach streamlines system design, dynamic analysis, and prototype installation, providing a fresh perspective on magnetic penta-stable vibration energy harvester design. The magnetizing current method is employed to accurately determine the system’s magnetic field and magnetic force. Stability analysis indicates that the multi-stability of the harvester is influenced by both the vertical magnetic force and equivalent linear elastic force, which can be effectively controlled by adjusting the system’s components. Dynamic simulations conducted under Gaussian white noise excitation confirm the penta-stable behavior of the system, and the dynamic responses verify that a shallower potential well depth contributes to the system’s ability to attain a higher output voltage. Experimental validations closely align with simulation results, providing strong evidence for the accuracy of the study’s findings. Furthermore, a practical application experiment demonstrates the harvester’s capability to power a hygrothermograph, highlighting its potential for real-world energy harvesting applications.

A self-tuned rotational vibration energy harvester for self-powered wireless sensing in powertrains

During conversion between mechanical and electrical energy within a machine, or vice-versa, vibrations (or perturbations of the rotational speed) are usually present. These vibrations can be converted into relatively small but useful amounts of electrical energy that can power wireless sensors. In this paper, a novel self-tuning concept of a rotational vibration energy harvester for energy conversion applications is presented. The design concept combines a self-tuned oscillator with an eccentric mass on a “tautochrone” path of motion so that its natural frequency matches a selected order of the rotational speed of a powertrain in order to harness the energy of rotational oscillations. This original vibration energy harvester design (which does not require protruding beams) enables the implementation of the concept for propulsion applications with the appropriate tuning condition. The mathematical modelling of the device and selection of the key design parameters suggest sufficient generated power to successfully drive an electronic circuit equipped with a temperature sensor. A physical prototype is manufactured and experimentally tested, validating the proposed design. The device is demonstrated to be capable of powering a wireless temperature sensor transmitting data every 2 s for a range of more than 1000 rpm of the shaft rotational speed. Higher data transmission rates could be achieved by optimising the design of the harvester, which currently has an overall volume <60 cm3.

Design of vibration energy harvesters with customized nonlinear forces

Nonlinear forces have been widely introduced into vibration energy harvesting to improve its performance. Generally, sources of nonlinearity include magnet forces, spring forces, geometric and material nonlinearity, etc. However, these nonlinear forces cannot be manipulated arbitrarily. It is very promising if the nonlinear forces can be customized according to requirements, in which the performance of the energy harvester can be further optimized. Therefore, the purpose of this study is to develop a kind of vibration energy harvester (VEH) that can customize the nonlinear forces. The nonlinear force customization device consists of a pre-compressed spring, a miniature bearing, and a raceway, which are designed according to the nonlinear forces. As an example, the device is installed at the end of a piezoelectric cantilever beam, and mono-stable, bi-stable and tri-stable energy harvesters are customized, respectively. Simulation and experiments prove its effectiveness. The nonlinear force customization device enables designers to obtain the desirable nonlinear forces for the vibration energy harvesters.

Acoustic Energy Harvesting Through Multilayer Piezoelectric Harvester Model

Low-power requirements of contemporary sensing technology attract research on alternate power sources that can replace batteries. Energy harvesters’ function as power sources for sensors and other low-power devices by transducing the ambient energy into usable electrical form. Energy harvesters absorbing the ambient vibrations that have potential to deliver uninterrupted power to sensing nodes installed in remote and vibration rich environments motivate the research in vibrational energy harvesting. Piezoelectric bimorphs have been demonstrating a pre-eminence in converting the mechanical energy in ambient vibrations into electrical energy. Improving the performance of these harvesters is pivotal, as the energy in ambient vibrations is innately low. In this paper, we propose a mechanism namely Multilayer-PEHM (Piezoelectric Energy Harvester Model) which helps in converting the waste or unused energy into the useful energy. Multilayer-PEHM contains the various layer, which is placed one over the other, each layer is placed with specific element according to their properties and size, the size of the layer plays an important part for achieving efficiency. Furthermore, this paper presents an audit of the energy available in a vibrating source and design for effective transfer of the energy to harvesters, secondly, design of vibration energy harvesters with a focus to enhance their performance, and lastly, identification of key performance metrics influencing conversion efficiencies and scaling analysis for these acoustic harvesters. Typical vibration levels in stationary installations such as surfaces of blowers and ducts, and in mobile platforms such as light and heavy transport vehicles, are determined by measuring the acceleration signal. The frequency content in the signal is determined from the Fast Fourier Transform.

A Nonlinear Concept of Electromagnetic Energy Harvester for Rotational Applications

Many industrial applications incorporate rotating shafts with fluctuating speeds around a required mean value. This often harmonic component of the shaft speed is generally detrimental, since it can excite components of the system, leading to large oscillations (and potentially durability issues), as well as to excessive noise generation. On the other hand, the addition of sensors on rotating shafts for system monitoring or control poses challenges due to the need to constantly supply power to the sensor and extract data from the system. In order to tackle the requirement of powering sensors for structure health monitoring or control applications, this work proposes a nonlinear vibration energy harvester design intended for use on rotating shafts with harmonic speed fluctuations. The essential nonlinearity of the harvester allows for increased operating bandwidth, potentially across the whole range of the shaft's operating conditions.

Damping ratio and power output prediction of an electromagnetic energy harvester designed through finite element analysis

This paper presents a novel and simplified method to predict the damping ratio and power output of a cantilever-based electromagnetic vibration energy harvester through finite element analysis. A strong relationship was determined between the mechanical damping of a structure and the resonant stress at the clamped end of the structure under critically damped condition, otherwise described as the critically damped stress. This relation was used as a basis to develop a material-specific damping stress equation. The equation was then integrated into FEA to analyse a certain electromagnetic vibration energy harvester design by considering the variation in damping and power output for every structural change. The effect of the phase difference on the power output of the electromagnetic harvester was also considered. The FEA design that recorded the highest power output prediction (11.1% higher than the initial structure) was then verified experimentally, displaying a good agreement with experimental results, recording an error of less than 5.0% for the amplitude and voltage evaluation and 8.0% for the power output assessment. Hence, this validates the accuracy of the proposed method in predicting not only the mechanical damping of regular cantilever beams, but also other cantilever beam-based structures.

A Novel Design to Increase the Power Output of an Electromagnetic Vibration Energy Harvester Using Finite Element Analysis

The concept of Internet of Things has prompted the need for a sustainable energy source to power wireless sensor networks. Vibration energy harvesting emerges as an applicable option. This paper presents a finite element analysis of a new electromagnetic vibration energy harvester design aimed to increase the power output of an electromagnetic vibration energy harvester by making the coil and a pair of magnets vibrate in the opposite direction, hence increasing the speed of the coil cutting through the magnetic flux of the magnets. The design consist of a regular cantilever beam And one uniquely shaped cantilever beam designed to move in the opposite direction to the regular beam under the same base excitation. Results show that due to the opposite motion, the speed of the coil moving through the magnetic flux for the new design is equal to the sum of velocities from the two individual beams. This lead to a 99.3% increase in power output generated from the new design when compared with the sum of the individual power outputs produced by the two beams. Further analysis demonstrates that the maximum power decreases if a time lag was introduced between the two beams, hence stating the importance of matching their natural frequencies.

Effects of Proof Mass Geometry on Piezoelectric Vibration Energy Harvesters.

Piezoelectric energy harvesters have proven to have the potential to be a power source in a wide range of applications. As the harvester dimensions scale down, the resonance frequencies of these devices increase drastically. Proof masses are essential in micro-scale devices in order to decrease the resonance frequency and increase the strain along the beam to increase the output power. In this work, the effects of proof mass geometry on piezoelectric energy harvesters are studied. Different geometrical dimension ratios have significant impact on the resonance frequency, e.g., beam to mass lengths, and beam to mass widths. A piezoelectric energy harvester has been fabricated and tested operating at a frequency of about 4 kHz within the audible range. The responses of various prototypes were studied, and an optimized T-shaped piezoelectric vibration energy harvester design is presented for improved performance.

Effects of electrical loads containing non-resistive components on electromagnetic vibration energy harvester performance

Abstract To further advance the existing knowledge base on rectified vibration energy harvester design, this study investigates the fundamental effects of electrical loads containing non-resistive components (e.g., rectifiers and capacitors) on electromagnetic energy harvester performance. Three types of electrical loads, namely (I) a resistor with a rectifier, (II) a resistor with a rectifier and a capacitor, and (III) a simple charging circuit consisting of a rectifier and a capacitor, were considered. A linear electromagnetic energy harvester was used as an illustrative example. Results have verified that device performance obtained from pure-resistive loads cannot be generalized to applications involving rectifier and/or capacitor loads. Such generalization caused not only an overestimation in the maximum power delivered to the load resistance for cases (I) and (II), but also an underestimation of the optimal load resistance and an overestimation of device natural frequency for case (II). Results obtained from case (II) also showed that it is possible to tune the mechanical natural frequency of device using an adjustable regulating capacitor. For case (III), it was found that a larger storing capacitor, with a low rectifier voltage drop, improves the performance of the electromagnetic harvester.

Design under uncertainty for reliable power generation of piezoelectric energy harvester

In recent years, vibration energy harvesters have been widely studied to build self-powered wireless sensor networks for monitoring modern engineered systems. Although there has been significant research effort on different energy harvester configurations, the power output of a vibration energy harvester is known to be sensitive to various sources of uncertainties such as material properties, geometric tolerances, and operating conditions. This article proposes a reliability-based design optimization method to find an optimum design of energy harvester that satisfies the target reliability on power generation. This optimum design of vibration energy harvester demonstrates reliable power generation capability in the presence of the various sources of uncertainties.

Survey of electromagnetic and magnetoelectric vibration energy harvesters for low frequency excitation

The main challenge in the design of vibration energy harvesters is the optimization of energy outcome relative to the applied excitation. This depends strongly on the used energy harvesting principle. Possible principles to generate energy from common existing vibration sources are electromagnetic, magnetoelectric, electrostatic and piezoelectric. At low vibration frequencies, electromagnetic and magnetoelectric energy harvesting techniques deliver energy with the highest efficiencies and are therefore the most promising principles. In this paper, an overview of the recent developments in the state of the art of vibration energy harvesters is presented. Mainly, electromagnetic and magnetoelectric principle are discussed and they have been classified relative to design aspects. Considering delivered energy and depending on the type of vibration excitation, reported converters are compared.

Modelling and development of a robust hybrid rotary-translational vibration energy harvester

In this article, a new hybrid rotary-translational vibration energy harvester design is investigated. The design employs two coils which increase the peak output power by ~34% compared with a previous single-coil design. Peak power is shown to increase from 167 to 223 mW under a root-mean-square host acceleration of 5.4 Hz and 500 milli- g (where g = 9.81 m/s2). The measured peak power density of the double-coil device is 7 mW/cm3, compared to 5.5 mW/cm3 for the original single-coil variant. The average power increased from 35 to 39.7 mW. Further to this, the device is made more robust through the inclusion of low loss wear resistant elastomer, and the effects of the wear-mitigation measures are examined.

Analysis and efficiency measurement of electromagnetic vibration energy harvesting system

This paper deals with the efficiency analysis of developed electromagnetic vibration energy harvesting systems. The efficiency analysis of this energy harvesting system is specified and a linear model of the vibration energy harvesting system is simulated to determine theoretical limits. The influence of individual parameters of vibration energy harvesters is evaluated by the simulation model. Three vibration energy harvesting devices, developed at Brno University of Technology, were measured and their efficiencies were consecutively calculated from the measured data. Vibration tests of these harvesters were done with a lightweight vibrating structure of a steel beam where the effect of the vibration energy harvester operation is noticeable. The effects of used electronics and power management circuit for different levels of excited mechanical vibrations are presented. Realized analyses and measurements will be used for future improvement of vibration energy harvester design; mainly in applications of lightweight vibrating structures where the vibration energy harvester can affect mechanical vibrations in feedback.

Design and Development of Low Frequency Vibration Energy Harvester for Wireless Sensor Networks

Motivated by wireless sensor networks technology for surveillance and tracking of animals, the energy harvesters are designed and fabricated. Since energy harvester is designed to harvest low frequency seismic noise, electromagnetic principle will be used in the harvester. It can be noted that structure undergoes small strains and thus piezoelectric based harvester is not suitable for low strains. Folded beam structure, circular spiral and square spiral geometries have been considered for the design of vibration energy harvester. Folded beam structure has been tested against experiments and it agrees well with the simulated results. Simulations performed on circular and square spiral geometries show that the first natural frequency is about 0.2Hz. Square coil was manufactured and tested which gave natural frequency of 0.29Hz.

Modeling and design of Galfenol unimorph energy harvesters

This article investigates the modeling and design of vibration energy harvesters that utilize iron-gallium (Galfenol) as a magnetoelastic transducer. Galfenol unimorphs are of particular interest; however, advanced models and design tools are lacking for these devices. Experimental measurements are presented for various unimorph beam geometries. A maximum average power density of 24.4 and peak power density of 63.6 are observed. A modeling framework with fully coupled magnetoelastic dynamics, formulated as a 2D finite element model, and lumped-parameter electrical dynamics is presented and validated. A comprehensive parametric study considering pickup coil dimensions, beam thickness ratio, tip mass, bias magnet location, and remanent flux density (supplied by bias magnets) is developed for a 200 Hz, 9.8 amplitude harmonic base excitation. For the set of optimal parameters, the maximum average power density and peak power density computed by the model are 28.1 and 97.6 respectively.

Model-based design and test of vibration energy harvester for aircraft application

This paper deals with a development process of a vibration energy harvesting device in aircraft applications. The vibration energy harvester uses ambient energy of mechanical vibration and it provides an autonomous source of energy for wireless sensors or autonomous applications. This application presents a complex engineering problem and the vibration energy harvester consists of precise mechanical part, electro-mechanical converter, electronics and a powered application. It can be perceive as a mechatronic system and a mechatronic approach was used for development of our vibration energy harvester. An essential step of development process is simulation modeling which is based on mechatronic approach. Presented model-based design of vibration energy harvester is very useful during development process and the whole development process of the autonomous energy source is presented in this paper. The main aim of the paper is an introduction of our development methodology and our approach is presented on a sample of the vibration energy harvester for aircraft applications under project ESPOSA.

A comparison of power output from linear and nonlinear kinetic energy harvesters using real vibration data

The design of vibration energy harvesters (VEHs) is highly dependent upon the characteristics of the environmental vibrations present in the intended application. VEHs can be linear resonant systems tuned to particular frequencies or nonlinear systems with either bistable operation or a Duffing-type response. This paper provides detailed vibration data from a range of applications, which has been made freely available for download through the Energy Harvesting Network’s online data repository. In particular, this research shows that simulation is essential in designing and selecting the most suitable vibration energy harvester for particular applications. This is illustrated through C-based simulations of different types of VEHs, using real vibration data from a diesel ferry engine, a combined heat and power pump, a petrol car engine and a helicopter. The analysis shows that a bistable energy harvester only has a higher output power than a linear or Duffing-type nonlinear energy harvester with the same Q-factor when it is subjected to white noise vibration. The analysis also indicates that piezoelectric transduction mechanisms are more suitable for bistable energy harvesters than electromagnetic transduction. Furthermore, the linear energy harvester has a higher output power compared to the Duffing-type nonlinear energy harvester with the same Q factor in most cases. The Duffing-type nonlinear energy harvester can generate more power than the linear energy harvester only when it is excited at vibrations with multiple peaks and the frequencies of these peaks are within its bandwidth. Through these new observations, this paper illustrates the importance of simulation in the design of energy harvesting systems, with particular emphasis on the need to incorporate real vibration data.

High power density vibration energy harvester with high permeability magnetic material

An alternative design of vibration energy harvester was demonstrated to significantly increase the output power density. This design had two magnetic solenoids fixed at two sides of a spring supported hard magnet pair with anti-parallel magnetization, which produced a spatially inhomogeneous bias magnetic field for switching the flux inside the solenoids during vibration. Experimental results showed an output voltage of 2.52 V and a power density 20.84 mW/cm3 at 42 Hz, with a half peak working bandwidth of 6 Hz. This vibration energy harvester design leads to high output voltage, power and power density that are critical for real applications.